I've been trying to find details of the orbital changes that are expected to occur leading towards the final lunar orbit. However it appears no strict timeline is available. It looks like the changes in
orbits will happen within safe time periods after appropriate preconditions are met. Of course I can be totally wrong and there could be a precise schedule of actions/events.
I did get this brochure on the ISRO website that gives some information of the timeline http://www.isro.org/pslv-c11/brochure/contents.htm. This is another ISRO website that discusses the Chandrayaan http://www.isro.org/Chandrayaan/htmls/home.htm.
Under the section "The Journey" the article speaks about the different orbits and the rough estimate of when the spacecraft will finally be into the steady lunar orbit. The Yaan is expected to pass through 7 orbital speeds before finally settling into the desired Lunar orbit of 100km height from surface of the moon.
Here I am going to attempt to track the stages that will finally make the Yaan go ga-ga 'round the moon :-), starting with *Time-T, the launch on 22-Oct-2008 at 6:22am* local time.**
Ø Earth Orbit1 - 255 x 22860 km - GTO - 22-Oct-2008
- The Yaan attained Geosynchronous Transfer Orbit soon after being launched on 22-Oct-2008. The precise times vary with various news articles giving the timings as 18.2, 18.9 and 19 minutes after lift-off.
- I would like to quote the following from an article on
Sify.com dated 23-Oct-2008: “The health of the spacecraft is normal and (it is) doing fine. Spinning in elliptical orbit once in every six hours and 30 minutes, it has completed four orbits and is in the fifth orbit,” the official told IANS.
Ø Earth Orbit2 - 300 x 37000 km - 1st raise - 23-Oct-2008
- As per
this Sify.com report the move into Earth orbit2 occurred on 23-Oct-2008 around 0900 hours by firing the satellite's Newton Liquid Engine was fired for about 18 minutes.
- The India Express too reported the 1^st increase in orbital height in
this news report. In the new orbit the spacecraft will take about 11 hours to complete one revolution around the earth, as against six and a half hours when it was in the GTO.
Ø Earth Orbit3 - 300 x 73000 km – ETO - 2nd raise – 25-Oct-2008
- The 2^nd orbit-raising maneuver was reported by
PTI news on 25-Oct-2008;once aging the 440 Newton Liquid engine was fired at 5:48 am for about 16 minutes.
- The
Economic Times also reported the rise. In this orbit Chandrayaan-1 takes about 25 and a half hours to go round the earth once
- Worthwhile to mention this statement by ISRO chairman G Madhavan Nair; "So far, Indian-made satellites have reached to a height of only 36,000 km. Today's firing has taken Chandrayaan-1 to something like 75,000 km. That's well beyond what we have reached so far. It was a good event, and done precisely".
Ø Earth Orbit4 - 300 x 387000 km - Lunar Transfer Trajectory - Trans Lunar Injection
Ø Earth Orbit5 - 2000 x 384000 km - Lunar Transfer Trajectory - Mid-Course Correction
Ø Lunar Orbit1 - 500 x 5000 km - Lunar Transfer Trajectory - Lunar Insertion Maneuver
Ø Lunar Orbit2 - 100 x 5000 km - Lunar Capture - Initial Orbit
Ø Lunar Orbit3 - 100 x 100 km - Final Orbit
PS: I also have a consolidated picture @
http://chandan.name/Chandrayaan-1.htm
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